1. Field of the Invention
A method for generating a wear resistant cutting edge on an end mill. In particular, the subject invention discloses a procedure for producing a wear resistant cutting edge on an end mill by grinding the cutting edges, radial and axial, ground up sharp and then, prior to a applying a physical vapor deposition (PVD) coating of protective material, the edges are honed or partially dulled. The partial dulling can be lighter or heavier, depending upon the exact materials utilized to fabricate the cutting tool and the material to be cut.
2. Description of the Background Art
Rotational end mills have been utilized for various cutting chores and have a long history. Various sharpening methods have been developed over the years. Many of the more successful sharpening processes involve the deposition of surface materials onto the end mills for strengthening the final cutting edges. When a traditionally sharpened end mill rotationally encounters hard substances such as stainless steels and related, similar, or equivalent nickel alloys, with or without other added elements, the cutting edges begins to chip as the cutting process occurs. As cutting continues the edges begin to dull. Frequently, chips from the cutting edge he end mill will adhere or stick, via generated heat interactions, to the dulling cutting edge and further roughen the edge for the next cutting rotation. Among the negative consequences associated with this traditional edge destruction or degradative process are a decreased life of the end mill, increased costs for the milling operation, and cuts into the milled materials that are less precise than may be desired or required for a particular final function.
Specifically, U.S. Pat. No. 5,467,670 discloses a chemical vapor deposition (CVD) process for attempting to keep the edges of rotary cutting tools sharp. The high temperatures in this process cause a chemical reaction to occur on the surface of the cutting tool. Generally, the process involves final grinding on all surfaces except the flank faces. All of the surfaces of the tool are then wear coated with a CVD process at a high enough temperature to embrittle the sharp, rough ground cutting edges. The flank faces are then ground to specification sharpness, thereby removing the embrittled layer on the flank faces while leaving the rake faces CVD coated. If desired, a final PVD wear layer coating may then be applied.
Disclosed in U.S. Pat. No. 4,945,640 is a wear resistant coating for sharp-edged tools and the like. Usually, a base layer of noble metal is formed on the surface followed by an intermediate layer of tungsten and a final coating of a mixture of tungsten and tungsten carbide.
U.S. Pat. Nos. 3,874,900 and 3,988,955 both relate methods for coating wear surfaces with vapor deposits.
U.S. Pat. No. 4,470,895 presents an ion plating method for depositing a coating. The method stop the application of the coating immediately next to where the cutting edge begins so as to leave the cutting edge not covered.
In U.S. Pat. No. 5,477,616 the body of a knife blades is coated with a hard material in such a manner as to permit the entire cutting edge to be formed from the harder material.
Six patent from Japan (Nos. 51-42,029; 51-42030; 55-120937; 55-131173; 55-144937; and 56-3152) illustrate the use of various compositions of hardening material on the surfaces of cutting implements.
The foregoing patents reflect the state of the art of which the applicant is aware and are tendered with the view toward discharging applicant's acknowledged duty of candor in disclosing information which may be pertinent in the examination of this application. It is respectfully submitted, however, that none of these patents teach or render obvious, singly or when considered in combination, applicant's claimed invention.